1. Vision Rehabilitation Centers, Dr. P. R. K. Prasad Center for Rehabilitation of the Blind and Visually Impaired, L. V. Prasad Marg, Banjara Hills, Hyderabad, India 500 034
2. Vision Rehabilitation Centers, Dr. P. R. K. Prasad Center for Rehabilitation of the Blind and Visually Impaired, L. V. Prasad Marg, Banjara Hills, Hyderabad, India 500 034; e-mail:
3. Public Health Ophthalmology, L. V. Prasad Eye Institute, L. V. Prasad Marg, Banjara Hills, Hyderabad, India 500 304